Cisco Phones suddenly not registering

Hi All

I have a cisco 7975 and a 7911 which were both connecting and working perfectly with FreePBX up until about Wednesday this week. For some reason they had lost connection with the freepbx system and were stuck in a registering loop.

The phones have been rock solid for over a year now since they were set up and connected, so this is very unexpected.

The system has the cisco patch applied.

So I am wondering how can I now get the phones to register again? the system doesn’t do auto updates but if it did is this even possible to cause the phones to de register?

I would love any help or suggestions as this is now extremely frustrating!!



Did you check that DHCP is providing option 66 for the phones?

Did you check the phone information, or manually configure one phone and enter the registration information to see if it works confirming if the above is either working or not?

Thats where I would start.

how do i check it is providing option 66? is this in the router?

I have checked the registration information and it should all be fine, the weird part is it was a rock solid connection and overnight just dropped out so its kind of inexplicable.

Depending on your router/firewall or wherever you provide DHCP from is where you have to check.

If you take phone and erase it, then plug it in, does it provision?
You can look at the log files to verify if it’s communicating with the PBX

Have you looked at any logging information?

Hi All

Just wanted to give everyone an update. It appears to be something to do with NAT. When setting this to never instead of No it resolved the problem.